Hot blast stove and blast furnace arrangement



HOT BLAST STOVE AND BLAST FURNACE ARRANGEMENT Filed April 8, 1963 2 Sheets-Sheet 1 III INVENTORS,

J/ICK HYDE FRED M. SCHWE/NBEPG BY g J M/K .dttomg March 30, 1965 J. HYDE ETAL 3, 75,816

HOT BLAST STOVE AND BLAST FURNACE ARRANGEMENT Filed April 8, 1963 2 Sheets-Sheet 2 1? x ii INVENTOR5 J/ICK HYDE 6' F250 M. SCI/WE/NBERG Ml 6314M the stove in this position.

nited. States This invention relates generally to hot blast stoves for a blast furnace and more particularly to a plurality of horizontal hot blast stoves having a common combustion chamber.

Heretofore, hot blast stoves for blast furnaces have been vertically disposed. Although the vertical position required a large number of internal structural supports and such accessories as a stove elevator to permit the equipment to be reached, the vertical position of the hot blast stoves was for many years advantageous because it was relatively easy to set the checker bricks'in place with In addition, prior to the use of increased pressures and temperatures the cost of vertical hot blast stoves was not excessive. In recent years, however, the trend has been toward using higher pressures in blast furnaces and higher temperatures in the blast to the furnaces. The increased temperature and pressure in the blast to the furnace requires a corresponding increase in the temperature to which the hot blast stoves are driven. This increase in temperature necessitated more costly refractory checkerwork and alloy steel supports for the checkerwork. It was also necessary to use a shell having a relatively large thickness to withstand the stresses imposed by the increased internal pressure.

In accordance with the present invention these difficulties are eliminated by placing the hot blast stoves in a horizontal position. The thickness of the shell can then be greatly reduced especially when the stove shell is constructed with dished ends which effectively withstands internal pressures. The stove elevator and the great number of internal structural supports can also be elimihated.

chamber.- For proper operation of the blast furnace, it

is generally necessary to use three hot blast stoves in sequence. While one of the hot blast stoves is supplying a hot blast of air to the blast furnace, each of the other hot blast stoves is being supplied with heat from its internal combustion chamber, and the heat is stored in checker bricks within the hot blast stoves.

- In accordance with the invention, a single external combustion chamber is used for all the hot blaststoves instead of the three internal combustion chambers formerly-used. This common external combustion chamber performs the function of the three separate combustion chambers heretofore used in that while one hot blast stove is being utilized to supply the blast furnace with a hot blast of air, the other two hot blast stoves are being heated by the combustion chamber.

The present invention thus eliminates two hot blast stove burners and combustion chambers with an accompanying reduction in the capital cost of the equipment. Since the internal combustion chambers are eliminated the size of the hot blast stoves can be considerably reduced, and a greater percentage of the internal volume of atent 'is also eliminated. Thus the checker bricks in accordance with this invention can be raised to temperature higher than heretofore used. The resulting greater heat storage capacity reduces the quantity of checkers required to maintain the desired hot blast temperature and thereby further reduces the size of the hot blast stoves.

A further advantage in the use of horizontal stoves is achieved by virtue of the fact that the horizontal stoves spread the load per square foot over a large area and this, plus the reduction in size and the elimination of two combustion chambers, elevators, burners, etc., reduces the heretofore necessary amount of piling and foundations for the stoves.

In accordance with the invention, three hot blast stoves are disposed in a horizontal position, the stoves may all be placed at the same elevation and adjacent to each other or they may be placed one above the other. Each hot blast stove is substantially filled with checker bricks. The ends of each stove may be dished for added structural strength. The hot blast stoves are connected to the bustle pipe of the blast furnace by a hot blast main having three branch lines, one for each hot blast stove. Each branch line from the hot blast main connects with one of the hot blast stoves through a valve means which can be operated to cut off the flow of gases from the stoves to the hot blast main. In operation, only a single hot blast stove will be operatively connected to the hot blast main at any time.

A single combustion chamber is provided for heating the hot blast stoves and this combustion chamber is connected to the hot blast stoves through the same valves that control the lines to the hot blast main. When these valves are positioned to close off the line between the hot blast stoves and the hot blast main, the valve between the combustion chamber and the hot blast stoves is open and thus two hot blast stoves are heated by the combustion chamber while the third hot blast stove is supplying a hot blast to the blast furnace through the hot blast main and the bustle pipe. If one of the hot blast stoves reaches the desired temperature it can be sealed ofi and all of the heat from the combustion chamber can then be directed to the other hot blast stove.

For more complete understanding of the invention reference may be had to the accompanying drawing in which:

FIGURE 1 is an isometric view of the hot blast stoves of the invention;

FIGURE 2 is a longitudinal cross-sectional view of a hot blast stove and the valve system therefor;

FIGURE 3 is a transverse cross-sectional view of a typical hot blast stove of the invention; and

FIGURE 4 is a transverse cross-sectional view of an alternate embodiment of the hot blast stove of the inven- 3 through common conduit 22 and branch conduits 24, 26 and 28.

Means including valves 31 32 and 34 are provided in conduits 24, 26 and 28 to connect the hot blast stoves alternately with the blast furnace or the combustion chamber 18. The connection with the blast furnace is accomplished by conduits 42, 44, 46 which lead from valves 30, 32, 34 to hot blast main 48 which in turn transfers the gases passing therethrough to bustle pipe 49 and tuyeres 50 and into the blast furnace 10. The valves 31), 32, 34 can be adjusted to either pass gases from the combustion chamber 18 through conduit 22 and the branch lines therefrom into the hot blast stoves or in the alternative to pass gases from the hot blast stoves through conduits 42, 44 and 46 to the hot blast main 43.

Each hot blast stove is provided with a conduit 36 (only one shown) which is used to remove gases originating in the combustion chamber from the hot blast stoves. These exhaust gases are then passed through conduit 36 to a stack 38. Conduit 36 is furnished with a valve 40 (FIGURE 2) for shutting otf the flow of gases between the hot blast stove and the stack 38 during the period that the hot blast stove is supplying a hot blast of air to the blast furnace.

The hot blast furnished the blast furnace is derived from a cold blast of air from a blower (not shown) through conduit 52 (FIGURE 2) and valve 54 to the hot blast stove. The cold blast of air from conduit 52 traverses the length of the hot blast stove and picks up heat from the heated checker bricks 72 within the hot blast stoves. During this period when the hot blast stove is delivering a hot blast of air to the blast furnace, valve 30 (FIGURE 2) is positioned to close off conduit 24 between the combustion chamber and the hot blast stoves, and the valve in this position allows the hot blast to be directed from the hot blast stove through branch line 42 to the hot blast main 48, bustle pipe 49 and tuyeres 50 and into the blast furnace 10.

The stoves 12, 14, 16 are capable of heating the blast to a temperature considerably higher than the maximum temperature at which furnace 10 operates. Therefore a portion of the hot blast to the furnace comes directly from the cold blast line 52 (FIGURE 2) to the hot blast line 42, 44, 46 via mixer line 58 and branch lines 60, 62, 64. Mixer line 58 branches off from the cold blast line upstream of the valve 54 and enters branch lines 42, 44, 46 through conduits 60, 62, 64 and valves 30, 32, 34. Each of the conduits 60, 62, 64 is provided with a valve 66, 68, 70. Adjustable mixer valves 66, 68, 71) are mounted in these branch lines to control the portion of the blast which takes this route and thus control the temperature of the blast reaching the furnace.

The hot blast stoves and their checker bricks can be of conventional design, typical are those shown in FIGURES 3 and 4. In FIGURE 3 the checker bricks 72 and the furnace wall 74 can be hexagonal in shape. In FIGURE 4, the checkers could be laid up in a series of concentric rings 76 within a cylindrical wall 78. The hot blast stoves of this invention are capable of being heated to temperatures as high as 4000 F. thus allowing a high hot blast temperature for use in blast furnaces operating at high pressure, since no problem of overheating structural supports exists in the novel arrangement of this invention; such problems limited the temperature of the vertical arrangement known heretofore.

In typical operation, the cycle has just been completed when stove 16 is cooled and stove 12 is fully heated by way of combustion chamber 18 to a temperature of about 4000 F. while stove 14 is partially preheated to a temperature of about 3750 F. At this time valve 30 is open to pass a hot blast from the hot blast stove 12 to blast furnace 10. Valves 32 and 34 are positioned to pass heating medium from combustion chamber 18 to hot blast stoves 14, 16. Valve .54 is open delivering a cold blast from a blower (not shown) to hot blast stove 12, and the equivalent valves (not shown) on hot blast stoves 14 and 16 are closed. Valve 40 on hot blast stove 12 is closed and the equivalent valves (not shown) on hot blast stoves 14 and 16 are open, thereby allowing cooled gases from the combustion chamber 18 to be exhausted through chimney 38.

The valve 54 (FIGURE 2) is thus open so that a cold blast of air from conduit 52 will enter hot blast stove 12 through conduit 53. This cold blast of air picks up the stored heat from the checker bricks 72 in hot blast stove 12. The resulting hot blast of air flows from stove 12 through valve 36 (FIGURES 1, 2) and then through conduit 42, hot blast main 48, bustle pipe 49 and tuyeres 50 into the blast furnace 10.

During the time the hot blast stove 12 is furnishing heat to the blast furnace, the other two hot blast stoves 14, 16 are being heated simultaneously by a flow of hot gases from combustion chamber 18. This is accomplished by passing the hot gases from combustion chamber 18 through conduit 22 and branch conduits 26, 28 through valves 32, 34- and into the hot blast stoves 14, 16. The heated gases pass through the hot blast stoves 14, 16 giving up their heat to the checker bricks therein and the gases exit from the hot blast stoves through conduits 36 and into stack 38.

The amount of the heat supplied to the hot blast stoves 14, 16 is regulated, as by the position of the valves, so that when the temperature in hot blast stove 12 has been depleted to a predetermined temperature of about 3500 F. the temperature in hot blast stove 14 has at this point reached a maximum predetermined temperature of about 4000 F. and the temperature in hot blast stove 16 will be at an intermediate temperature of about 3750 F.

At this time valve 54 in conduit 52 of hot blast stove 12 is closed thereby shutting off the cold blast of air into hot blast stove 12. Valve 30 is repositioned to allow passage of heated gases from combustion chamber 18 to enter the hot blast stove 12 through conduit 24, and valve 40 in conduit 36 of hot blast stove 12 is opened to allow the cooled gases to be delivered to the stack 38. Simultaneously, a cold blast of air is delivered to hot blast stove 14 through its conduit 52 and valve 54, and valve 32 on hot blast stove 14 is repositioned to shut off the flow of gases from the combustion chamber into the hot blast stove 14 and allow the passage of gases from the hot blast stove 14 through the valve 32 into branch line 44, hot blast main 48, bustle pipe 49, and tuyeres 50 to the blast furnace 10. At this time the valving associated with hot blast stove 16 is not changed.

Operation is continued with hot blast stove 14 furnishing the hot blast for the blast furnace while hot blast stoves 12 and 1.6 are being heated by the combustion chamber until the temperature in hot blast stove 14 is depleted a predetermined amount. At this time the valves are repositioned to allow the hot blast stove 16 to supply the blast to the blast furnace, and simultaneously the hot blast stoves 12 and 14 are heated by the gases from the combustion chamber 18. The above cycle is then repeated.

During the delivery of the hot blast from any of the hot blast stoves to the blast furnace, the temperature of the hot blast is regulated to the desired temperature by way of the appropriate mixer valves 66, 68, 70 whereby a portion of the cold blast from conduit 52 flows through valves 66, 68, 7'9 and the valves 30, 32 or 34 controlling the hot blast stove which is delivering the hot blast to the blast furnace. As the temperature of the checker bricks in the hot blast stove is reduced as it heats the cold blast of air travelling therethrough the amount of air flowing from the cold blast line to the mixer valve is adjusted to maintain a substantially constant hot blast temperature in hot blast main 48.

The invention as described above provides a low cost,

efficient installation for providing a hot blast for a blast furnace. The invention provides hot blast stoves which are capable of being heated to temperatures significantly higher than those heretofore known while eliminating a large number of internal structural supports and accessories and decreasing the size of the hot blast stoves without decreasing their capacity.

We claim:

1. In combination with a blast furnace, a plurality of hot blast stoves and a single combustion chamber separate from and arranged outside of said hot blast stoves, means to support said combustion chamber in a horizontal attitude, each of said hot blast stoves being substantially cylindrical in shape and horizontally disposed, first means for alternately operatively interconnecting said combustion chamber with each of said hot blast stoves, second means for alternately operatively interconnecting each of said hot blast stoves with said blast furnace, said first means including conduit means and valve means, said second means including conduit means connecting said blast furnace with said hot blast stoves through said valve means, means for supplying a cold blast of air to each of said hot blast stoves for use when said hot blast stove is delivering a hot blast to said blast furnace, and

means for removing exhaust gases from each of said hot blast stoves for use when said hot blast stoves are being treated by gases from said combustion chamber.

2. In combination, a blast furnace, three horizontally disposed hot blast stoves, and a single combustion chamber separate from and arranged outside of said hot blast stoves, means to support said combustion chamber in a horizontal attitude, means for selectively connecting said combustion chamber with two of said hot blast stoves for supplying heat to checker brick in said stoves, means for supplying a cold blast of air to the remaining hot blast stove for heating of the cold blast to produce a hot blast, and means for feeding said hot blast to said furnace.

3. In combination with a blast furnace:

(a) a plurality of hot blast stoves adapted to supply hot blast air to said furnace;

(b) means supporting said hot blast stoves in a substantially horizontal attitude;

(0) conduit means communicating said furnace with said stoves;

(d) a single combustion chamber separate from and arranged outside of said hot blast stoves adapted to supply heat to said hot blast stoves; and

(e) means to support said combustion chamber in a horizontal attitude;

(7) conduit means communicating said combustion chamber with said hot blast stoves whereby heat is supplied to at least one of said stoves selectively at a time.

References Cited by the Examiner UNITED STATES PATENTS 340,110 4/86 Gordon 26319 358,500 3/87 Strobel 26319 446,501 2/91 Wetherow 263-l9 759,171 5/04 Gaines 26319 X 1,074,097 9/19 Stevens 216---l4 1,303,155 5/16 Bingham 266-14 1,518,258 12/24 Fahrenwald 26315 1,592,616 7/26 Noyes et al. 263-19 X 1,716,572 6/29 Wright 26315 1,924,936 8/33 Lehr 26319 1,941,446 12/33 Isley 26319 2,351,661 6/44 Carter of al. 263-15 2,505,861 5/50 Johnson 263-19 2,931,635 4/60 Braun et a1 26319 2,936,162 5/ Coberly 263-57 3,124,337 3/64 Fritz 263l9 CHARLES SUKALO, Primary Examiner:

JOHN J. CAMBY, Examiner. 

2. IN COMBINATION, A BLAST FURNACE, THREE HORIZONTALLY DISPOSED HOT BLAST STOVES, AND SINGLE COMBUSTION CHAMBER SEPARATE FROM AND ARRANGED OUTSIDE OF SAID HOT BLAST STOVES, MEANS TO SUPPORT SAID COMBUSTION CHAMBER IN A HORIZONTAL ATTITUDE, MEANS FOR SELECTIVELY CONNECTING SAID COMBUSTION CHAMBER WITH TWO OF SAID HOT BLAST STOVES 